At present, stretch spring manufacturers of processing equipment and production lines toward CNC) and computer control CNC program depth development. With the change of stretch spring material and several new shapes, the processing process also developed.

1) The outer diameter, pitch and diameter of the stretch spring are changed, and the suspension stretch spring can achieve molding free processing. Since the development of the three-variable stretch spring, tapered steel rod has been used in the winding of CNC lathe, and the yield and price are unreasonable. Change to the hot state through the spring coiling machine, control roll speed and tension, so as to obtain the required cone shape, and the use of processing waste heat quenching.

2) Hollow stable drawing spring rod adopts low carbon steel sheet to be formed by welding.

3) The torsion bar is made of high purity 45# steel, which is quenched at high frequency to obtain high surface hardness and large residual compressive stress, thus improving the fatigue life and anti-relaxation ability.

4) Sheet stretch springs used in electronic products are basically formed by stamping and automatic bending. At present, it mainly develops the joint technology of composite materials.

(1) Cold forming process of drawing spring

1) One-time automation of cooling forming process. Cooling forming machine has been developed to 12 claw spring machine. In (0. 3~14) The steel wire within the range of mm is basically formed once in the 8-claw spring forming machine. At present, rapid development of forming process equipment.

(1) To improve the forming speed, the main development trend is to improve the forming equipment, namely production efficiency;

(2) By improving the precision of equipment parts and strengthening the effect of heat treatment to improve the durability of equipment;

(3) Add sensors and laser rangefinder to CNC forming machine program for automatic closed-loop control manufacturing process.

2) Scope of cooling forming process. At present, large wire diameter stretch spring, spring coiling machine, large specification up to 20mm,=2000MPa, winding ratio 5. The cold forming process of Minic-Block spring and eccentric stretch spring with diameter or equal outside diameter is limited.

(2) Hot forming process of drawing spring

1) Ability of thermal forming process speed development. At present, China's (9~25)mm specification of the forming spring machine only CNC computer X2 axis spring coil machine, large speed can produce 17 pieces per minute. Compared with the development of the domestic gap is larger.

2) Control ability of hot forming process of large tensile spring. Due to the only CNC calculation of X2 axis hot spring coil machine shape control less than three directions, the accuracy is poor; And at present, there is no automatic rod rotation control and adjustment, so the hot coil drawing spring forming technology level and ability is low. Therefore, the precision level and surface oxidation decarburization level of the stretch spring are also lower.